Conventionally, in buildings such as office buildings or tenant buildings, a sensing result of presence or absence of people is acquired by using an image captured by an image sensor. Then, in accordance with the sensing result, power controlling of electric devices such as lightings and air conditionings is performed. When such power controlling is performed, it is necessary to perform various settings by associating electric devices, which are to be the target of controlling, and image sensors, which have jurisdiction over the electric devices, with each other. However, such operation may become cumbersome due to an increase in the number of the electric devices and the image sensors. Accordingly, there has conventionally been proposed a technique to detect an installation position of a device (lightings) installed at the ceiling surface, by using a position detection device that detects the installation position by a reception level of a radio signal.
However, according to the conventional technique, it is necessary to prepare a dedicated device for specifying the installation position. Thus, there is a room for improvement in terms of efficiency in the setting operation.